Desterolation



Patented July 11, 1950 DESTEROLATION Kenneth C. D. Hickman, Rochester, N. Y., as-

signor, by mesne assignments, to Eastman. Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application August '1, 1946, Serial No. 688,963

4 Claims. 1

This invention relates to an improved method of removing sterols from oil concentrates, and portions thereof, and particularly to a process which crystallizes sterols so they may be easily removed by filtration.

Sterols are usually present in vegetable oils to an extent not exceeding 1%. Whenever the tocopherol fraction is, concentrated from a vegetable oil, for example by high-vacuum unobstructed-path distillation: orb saponification of glyceride fractions, most of the sterols are found in the tocopherol concentrate, the sterol percentage frequently being above 30%. The term oil concentrate as used in this application is defined as a vegetable oil which has been put through a process to obtain a tocopherol concentrate containing in excess of sterols.

Past practice for sterol removal hasbeen to add 3 or 4 parts of acetone or l0-15 parts of methyl alcohol to the oil concentrate and cool to temperatures of the order of C. After allowing to stand for about 15 hours the precipitated sterols are removed by filtration. Thismethod leaves a substantial proportion of the sterols in solution.

This invention has for its object to provide a process for separation of sterols from oil concentrates bythe use of minimum quantities of solvent. Another object is to produce sterols of high purity. A iurther objectis to specify -a ;procedure by which sterols may be rendered-less soluble. A still further object is to improve the state of the art. Other objects will appear hereinafter.

These and other objects are accomplished by my invention which includesv contacting a sterolcontaining fatty oil with relatively small quantities of methanol, or ethylene 'g'lycol 'to render the sterol fraction less soluble and more easily crystallized.

In the followin examples and description I have set forth several of the preferred embodiments of my invention but it is to be understood, that these are given for the purpose of illustration and not in limitation thereof.

In the course of my investigation of ways to remove sterols from oil concentrates I have discovered that methanol and ethylene glycol act upon sterols to render them less soluble in oil concentrates. The mechanism by which this is accomplished is not clear but apparently the sterols enter into loose combination with the additive. This is evidenced by the fact that sterols crystallize in the form of needles from acetone solutions whereas alcohol-sterol crystals are in the form of plates.

The precipitant effect of methyl alcohols or ethylene glycol cannot be attributed to their presence as solvents, The quantities added are small, for example 1 to 10%, and .most of the alcohol adds to the sterol fraction and is precipitated upon subsequent filtration.

In amounts below about 10% by weight based on the weight of the oil being treated, methyl alcohol and ethylene glycol dissolve in the oil, forming a single liquid phase. The single liquid phase system has the advantages of eflectingihtimate contact between all of the solvent and the oil and greatly lessens the fire hazard which is present when larger amounts of solvent are em ployed forming .a two phase liquid system.

If the material to be :desterolated contains over 2.0% sterols, I find it moreconvenient to desterolate in two steps. Oil concentrates of over 20%v sterol content will usually be semi-solid or solid due to the precipitation of excess sterols. Suchan oil may be heated slightly above the temperature required to effect solution of the sterols and then cooled slowly over a period of 24 to '72 hours to room temperature. Slow cooling, preferably without. stirring, allows some of the sterols to precipitate in uniform crystal size and structure. The material may then :be further processed by passage through a grinder, such as a simple meat grinder, to release any oil entrained in the interstices of the sterol crystals. The resulting mushy mixture :is filtered to remove the separated sterols.

The. filtrate from the above operation, .or the original oil concentrate if less than 20% sterols are present, is contacted with methyl alcohol, .or ethylene :glycol in an amount not exceeding an equal weight of the oil concentrate and prefer-- ably about, 102% by weight of the oil concentrate. contact is preferably made at a temperature near thevaporizing temperature of :methyl alcohol, or ethylene :glycol. depending on which is .used. The efiect of increasing temperature is to improve crystal quality and yields. Lower temperatureor not heating at all results improved separation aver theprior art but the yield and. quality of the crystals are inferior to those produced by hot mixing with the additive.

If the initial sterol content of the oil concentrate is over 20%, alcohol or glycol may be added in a single-step process. However, in this event greater quantities of tocopherols are enmeshed in the sterols and filtration becomes a time-consuming step. The two-step process is therefore preferable.

The material is cooled slowly until the sterols are precipitated, the time of cooling depending crystal structure.

After the material has cooled the precipitate sterols are separated, preferably by filtration. If

the mixture is of a solid nature due .to large amounts of sterols, a grinding step may precede;

the filtration. i Lower temperatures can be employed, especially when the stearine content is low;;as-in soybean concentrate, with the attendant benefit of.'-pro-,

ducing a filtrate with lower sterol content. The filtration can be carriedon at a higher temperature when the stearine content of the oil is high, as in'a to'copherol concentrate obtained byhigh- Vacuum: distillation of deodorizeisludge; This will 'notlremove as much sterol from the'oil but the sterol will .be of a higher purity with a smaller quantity of stearinepresent. 7 There are marked advantages to be gained by my method ofdesterolation. First, large volumes of solvent are not required; Second, an elaborate cooling system isnot necessary, although-cooling the mixture below room 'temperature will increase yields. Thirdly, a. single liquid phase system is formed with a resultant enhancement of desterolation and avoidance of fire and explosion hazards encountered where asolvent layer is present.

Example 1 .-1 kg. soybean concentrate containing.:28%.sterols was heated in a beaker to-70 C. and 40 cos. of methanol (about 3.2% by weight of alcohol basedon the-weight'of concentrate treatedl-were added withrapid stirring, The beaker was set aside in the cold room (4 C.) for four hours, the contents-of the beaker were broken up with a spatulaand filtered on the Buchner funnel; There resulted a-clear brown filtrate'containing 7.1% sterols z Example 2.-A soybean concentrate produced by. subjecting soybean oil to high-vacuum unobstructe'd-path distillation weighing 181 kg'., containing 156 mg/grof tocopherol and 34.4% sterol washeated to 90C. and cooled slowly for '3 days. When the concentrate reached room temperature it wasground in a meat grinder and filtered on large Buchner funnels; The filter cake amounted to 67.7 kg..containing71.5 mg./g. of tocopherol and 68.3% sterol. .The filtrate weighed 111 kg.

and had. 204 mg./g.h of tocopherol and 14.4%

sterols. l A .1

Thefiltrate washeated to 65 C. and'4=% by weight of methanol added below the surface while stirring. The container was lagged for 18fhours and cooled slowly-for 2 more days. :rh moona mass was reground" as before and filtered on a Buchner funnel. r--..'lhe cake weighed ll k'guand contained-63.9% .ste'rolsrand 77.6% mg./g. of tocopherol. The filtrate was a clear, sparkling oil amounting to.97.3 kg. with 208 mg./g. of tocopherol and 6.27 sterols.

Example 3.A tocopherol concentrate obtained by the high-vacuum distillation of deodorizer sludge weighing 641 g. and containing 11.3% sterolswas filtered in abasket centrifuge and 79 g. of cakeremoved. A'--l62'-grarn' portion of the filtrate was heated to 63 C. and 18.5 g. of methyl alcohol calculated as 4% by weight of alcohol based .on the weight of filtrate being treated was added below the surface while the mixture was being stirred..- The mixture was allowed to stand overnight,v after which the material was filtered. --The--cake-weighed515 g. and the filtrate 404 g.,

7.7 of whichwassterol.

EgramplaQ- -AZOO gram sample of tocopherol concentrate produced by high-vacuum unobstructedepath distillation of soybean oil and containing l-'-12% sterols was heated to 65 C. and

3 grams of ethylene glycol (calculated 4% by weightethylene-glycol basedon weight of concentrate'being treated) was added below the surface. The mixture Wasstirred for 2 minutes and cooled slowly to'room temperature. Filtration removed 7.3 grams of sterols.

'WhatIclaim is: a

1. The method of desterolating an oil concentrate which comprises dissolving in'said concentrate from'1-l0% by weight, based on the weight of Said-concentrate, of a'substance selected-from,

the group consisting of methyl alcohol and ethylene glycol and thereby precipitating sterols from said concentrate.

' 2. The method 'of' desterolating an oil concentrate which comprises dis'solving'in said concentrate from 1-10% by weight, based on the weight of said concentrate,-of'methyl alcohol and thereby precipitating sterols therefrom.

3. The methodof desterolating an oil concen trate which comprises dissolving in said concentrate from 1-10%--by weight based on the weight of said concentrate, o'fja substance selected from the group consistingf'of methyl alcohol and ethylene glycol, at a'- temperature below the vaporization temperature of said substance, cooling the resulting mixture andthereby precipitating sterols therefrom, and thereafter separating the precipitated sterols'from the liquid out of which aid sterols precipitated.

'4. The method ofdesterolating an oil concentrate which comprises dissolving in said concentrate from about 3 to about 4 by weight, based on the weight-"of said concentrate, of methyl alcohol and thereby precipitating sterols therefrom.

I KENNETHC. D. HICKMAN.

UNITED STAT S PA'IENTS Number Name Date 2,046,345 SchWieger July 7, 1936 Certificate of Correction Patent No. 2,515,041 July 11,1950 i KENNETH 0. D. HICKMAN i It is hereby certified that error appears in the printed specification of the above mmbered patent requiring correction as follows:

7 Column 3, line 63, for 77.6% mg./g. read 77'. 6 m g./g.; column 4, line 9, before the word calculated insert an opening parenthesis; lme 10, after treated insert a closing parenthesis; I v

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of thecase in the Patent Ofliee,

Signed and sealed this 17th day of October, A.D. 1950.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents. 

1. THE METHOD OF DESTEROLATING AN OIL CONCENTRATE WHICH COMPRISES DISSOLVING IN SAID CONCENTRATE FROM 1-10% BY WEIGHT, BASED ON THE WEIGHT OF SAID CONCENTRATE, OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OR METHYL ALCOHOL AND ETHYLENE GLYCOL AND THEREBY PRECIPITATING STEROLS FROM SAID CONCENTRATE. 